线性结构3 Pop Sequence（PAT）

Given a stack which can keep M numbers at most. Push N numbers in the order of 1, 2, 3, ..., N and pop randomly. You are supposed to tell if a given sequence of numbers is a possible pop sequence of the stack. For example, if M is 5 and N is 7, we can obtain 1, 2, 3, 4, 5, 6, 7 from the stack, but not 3, 2, 1, 7, 5, 6, 4.

Input Specification:

Each input file contains one test case. For each case, the first line contains 3 numbers (all no more than 1000): M (the maximum capacity of the stack), N (the length of push sequence), and K (the number of pop sequences to be checked). Then K lines follow, each contains a pop sequence of N numbers. All the numbers in a line are separated by a space.

Output Specification:

For each pop sequence, print in one line "YES" if it is indeed a possible pop sequence of the stack, or "NO" if not.

Sample Input:

5 7 5
1 2 3 4 5 6 7
3 2 1 7 5 6 4
7 6 5 4 3 2 1
5 6 4 3 7 2 1
1 7 6 5 4 3 2

Sample Output:

YES
NO
NO
YES
NO

题意

第一行输入 M, N，T

M代表栈的容量，N为序列长度，T为测试组数

我们可以向容量为M的栈中按照1 ， 2， 3..的顺序推入 1 ，2,  3.. ， 可以任意弹出。问能否输出给定序列。

样例 5 6 4 3 7 2 1

推入 1 2 3 4 5 ， 弹出 5， 此时 1 2 3 4

输入 6 ，推入 6， 此时 1 2 3 4 6 ， 弹出6 ，此时 1 2 3 4

输入 4 ，弹出 4，此时 1 2 3

输入 3 ，弹出 3，此时 1 2

输入 7，推入 7 ， 此时 1 2 7，弹出 7，此时 1 2

输入 2， 弹出 2 ， 此时 1

输入1 ，弹出 1. 输出 YES！

直接模拟题意解决

#include<iostream>
#include<cstdio>
#include<stack>
using namespace std;
int main(){
	int n,m,t;
	scanf("%d%d%d",&n,&m,&t);
	stack<int>st;
	for(int i = 0;i<t;i++){
		int tmp = 1;
		bool False = 0;
		for(int j=0;j<m;j++){
			int input ;
			scanf("%d",&input);
			while(st.size() <= n && !False){ //满足条件就不断推入 1,2,3...
				if(st.empty() || st.top() != input)
					st.push(tmp++);
				else if(st.top() == input){ //如果栈顶元素与输入的一样了，就弹出。
					st.pop(); break;
				}
				if(st.size() > n)
				{
					False =  1; break; //超过栈的范围了
				}
			}
		}
		if(!False)
			printf("YES\n");
		else
			printf("NO\n");
		while(!st.empty())
			st.pop();
	}
	return 0;
}